Spin-orbit coupling induced structural stability and semi-metallic state in La3 Ir3 O11

Abstract La 3 Ir 3 O 11 crystallizes in a cubic symmetry with its structure composed of electronically active IrO 6 octahedral motifs, which are corner and edge shared. Empirical considerations suggest Ir to be in the +4.33 valence state in La 3 Ir 3 O 11 , thereby anticipating the material to be a good conductor primarily due to the presence of holes in the crystal field split t 2 g bands of the Ir 5 d manifold. However, a comprehensive investigation of the electronic structure by means of first principles calculations find La 3 Ir 3 O 11 to be a spin-orbit driven semi-metallic iridate, with its Fermi energy comprised of both hole and electron bands. The properties of the electron-hole asymmetry in La 3 Ir 3 O 11 is clearly manifested in the temperature dependent variation of electrical conductivity and Seebeck coefficient, which are calculated using the Boltzmann transport theory. Besides, finding that Fermi energy is positioned in a steep valley like feature in the density of states spectra, the calculations also predict that both hole and electron doping would induce a semi-metal to metal transition in La 3 Ir 3 O 11 .